Question: what the conditions of wiping the feet over the socks in wudhu?
Answer: They must be suitable for travel. This means that they should be made of leather, or if not, they should be thick enough stand by themselves to above the ancle (I.e. they would stand if left on the floor like a shoe). This means that one cannot wipe regular thin socks as you see some people do.
They must cover all the foot to above the ancle, and they must have been worn while having wuduu'. The maximum time for wiping is 24 hours as a settler and 72 hours as a traveller. For more detail, click here and look under "Purification" for an article on this topic.
... and Allah knows best.